One electrophotographic printer known in the art is a color printer comprising a plurality of photosensitive members for each of the plurality of colors used by the printer, and a plurality of corresponding developing units for supplying toner respectively to the photosensitive members. This color printer can switch between a monochrome mode for forming black-only images, and a color mode for forming color images.
One such color printer that has been proposed includes drum cartridges, each of which has a photosensitive drum, and developer cartridges respectively mounted on the drum cartridges. In this printer, pressing levers are provided on the drum cartridges for constantly pressing the developer cartridges toward the respective photosensitive drums. A separating member is also provided in a main casing of the printer. When the printer is switched from the color mode to the monochrome mode, the separating member presses bearing members holding the shafts of developing rollers in the respective developer cartridges for the colors yellow, magenta, and cyan, thereby urging the bearing members in a direction away from the corresponding photosensitive drums. As a result, the developer cartridges are separated from the photosensitive drums against the force of the pressing levers.